If you’re melting down old soft plastic lures, put them in the cup in place of the resin.
Most fish food is either green or orange, so these colors are a great choice. Match the hatch. Look for baitfish, or other types of possible bait living in the area to be fished, and match their colors.
It may take several tries before you learn to fill the mold to the right level.
If the lure does set in a crooked position, you can melt it down and re-pour it.
As you trim the excess, gather it together. You can melt it down and add it to your next soft plastic lure, or you can add the shavings at the very end to add highlights to lures of a contrasting color.